| At present,all kinds of intelligent equipment mostly rely on the battery power supply inside the system.The commonly used power supply methods include plug wired power supply and battery replacement.There are problems such as relying on manual operation,frequent recycling and charging,easy wear of plug and plug devices and contact sparks.The appearance of Inductively Coupled Power Transmission(ICPT)technology has effectively solved various deficiencies existing in the traditional power supply mode,and has been widely applied in many fields such as electric vehicles,medical equipment and household appliances.Based on the principle of magnetic field coupling,ICPT technology realizes the "no electrical connection" transmission of electric energy from the power source to the electrical equipment.Because the primary and secondary sides of the system are totally separated,how to achieve high-speed and stable wireless communication between the primary and secondary sides has become one of the difficult problems in the research of output voltage feedback,load identification,foreign object detection and other technologies.Therefore,this paper proposes and studies a Simultaneous Wireless Power and Information Transfer(SWPIT)technology based on the harmonic characteristic of soft-switching inverter,in order to achieve high-speed and stable wireless information transmission between the primary and secondary sides of the ICPT system without affecting the power transmission topology and performance of the system.Firstly,this paper summarizes and analyzes the ICPT system topology,high frequency inverter and synchronous transmission mode of power and information,and summarizes the advantages and disadvantages of various existing technologies.In order to reduce the switching loss of high frequency inverter in SWPIT system and improve its reliability,stroboscopic mapping model and fixed-point theory was adopted to obtain the operating frequency points of soft-switching inverter.The influence characteristics of different soft-switching frequencies on the power transfer characteristics of the system are compared.In order to maximize the power transfer capacity of the system as the design criterion,the selection basis of the optimal soft-switching frequency of the system is given.Secondly,the modulation and demodulation schemes of SWPIT technology are compared and analyzed in detail,and the method of realizing signal modulation and demodulation by binary frequency shift keying and incoherent demodulation is determined.According to the harmonic characteristics of the output current of softswitching inverter,a novel SWPIT technology which uses fundamental wave to transfer power and harmonic wave to transfer power information is proposed.Based on the Deviation Frequency Deviation Effect(DFEE)of harmonic to basic wave,this technology realizes SWPIT based on 2FSK modulation strategy by adjusting the working frequency of the inverter.An optimal design method of signal detection circuit is proposed,which can effectively reduce the interference between the information and the power transmission channel.On the basis of maintaining the constant output voltage of the system,a higher signal-to-noise ratio can be obtained.Finally,the simulation platform of Simulink and the experimental platform of SWPIT system are established to verify the validity of the proposed SWPIT technology based on the harmonic characteristics of the operating point of the inverter softswitching,and the correctness of the optimization design method of the information detection circuit.The experimental results show that when the load output power is52.5 W,the information transmission rate can reach 16 kbps,the load voltage fluctuation is less than 3%,and the overall efficiency of the system can be maintained above 90%.81 figures,13 tables and 95 references are included in this thesis. |
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